This section provides background information related to the present disclosure which is not necessarily prior art.
Some low power and medium power server power supplies are designed for wide range AC input voltages ranging from 90V AC to 265 VAC, for 120V and 230V utility lines. However, some data center applications are designed mainly for high line operations where the efficiency and power factor performances at high line AC inputs need to be maximum. Furthermore, data center applications demand high efficiency with high power factor at light load conditions (approx. 10% to 50% load).
In prior art PFC systems, the overall efficiency of the systems is compromised to enable the front end power factor correction boost converter systems to operate at two widely separated input AC voltages (i.e. low line and high line).
A prior art power factor correcting boost converter system 100 with a single power rail operating at two widely separated AC input voltages is illustrated in FIG. 1. The design requirements of a boost inductor L1, a switch Q1 and a boost diode D1 are different when operating at two widely separated AC input voltages. However, since there is a single power rail, the system works at a compromised efficiency.
Various techniques have been used to improve the power factor of a power supply.